In the field of ambient air heating by using a portable fuel heater, devices are known comprising a combustion chamber, often cylindrical in shape, inside of which a liquid or gas fuel is conducted together with an oxidizing air flow to perform a combustion. The oxidizing air flow rate inside the combustion chamber is limiting because it must be in an adapted air/fuel ratio such as to optimize the quality of the combustion. Therefore, in order to obtain a high amount of heated air, a second air flow should be used, which is not involved in the combustion and which externally laps the combustion chamber. Such a flow operatively subtracts heat from the combustion chamber and transfers it to an environment to be heated.
In certain, particularly burdensome applications, for example when a very large environment is to be heated under extreme environmental conditions, for example a mine or a worksite at a high altitude, with outside temperatures well below 0° C., sometimes even up to −40° C., there is a need to generate a flow of hot air with a high flow rate, and at the same time there is a need to transfer a high heat amount from the combustion chamber to such an air flow.
These are contradictory needs, because the higher the speed of the air flow which flows laps the combustion chamber, the lower the heat amount that such a flow is capable of receiving from the combustion chamber.
Heaters from the known art do not allow these needs to be met simultaneously.